Polygenic Risk for Externalizing Disorders: Gene-by-Development and Gene-by-Environment Effects in Adolescents and Young Adults

In this project, we aimed to bring large-scale gene-identification findings into a developmental psychopathology framework. Using a family-based sample, we tested whether polygenic scores for externalizing disorders—based on single nucleotide polymorphism weights derived from genome-wide association study results in adults (n = 1,249)—predicted externalizing disorders, subclinical externalizing behavior, and impulsivity-related traits among adolescents (n = 248) and young adults (n = 207) and whether parenting and peer factors in adolescence moderated polygenic risk to predict externalizing disorders. Polygenic scores predicted externalizing disorders in adolescents and young adults, even after we controlled for parental externalizing-disorder history. Polygenic scores also predicted subclinical externalizing behavior and impulsivity traits in the adolescents and young adults. Adolescent parental monitoring and peer substance use moderated polygenic scores to predict externalizing disorders. This illustrates how state-of-the-science genetics can be integrated with psychological science to identify how genetic risk contributes to the development of psychopathology.